President-elect Barack Obama and Vice President-elect Joe Biden arrived at Washington’s Union Station and emerged from the “Obama Express” at just after 6:40 p.m. this evening. The “whistle stop tour” began earlier today in Philadelphia, then stopped in Biden’s home of Wilmington, Delaware, and also in Baltimore for a public event at the War Memorial Plaza. Obama gave speeches at events at each of the stops along the way, but opted to hop directly…